Process for the manufacture of carboxylic acid anhydrides



Patented July 9, 1935 I i UNITED STATES PATENT OFFICE Martin de Simo, Berkeley, Calif., asslgnor to Shell Development Company, San Francisco, Calif a corporation of Delaware No Drawing. Application November 3, 1931,

Serial No. 572,877

14 Claims. (01. 2 -123 My invention relates to a process for the manuof the separate anhydrides, one of which is lower facture of acid 'anhyd'rides and more particuboiling and the other higher boiling than the larly is concerned" with the preparation thereof original mixed anhydride. The fractionating' V by the utilization of ketene. column and reflux condenser are so designed and I am aware of theexisting processes wherein operated that only the lower boiling anhydride 6 (1) P0013 is reacted with the sodium salt of the is removed as distillate. Any mixed anhydride, fatty acid to give the anhydride of the same; (2) if distilled, is returned to the still and ultimately an acid chloride andthe sodium salt of the acid converted, with the result that finally the subare reacted forthe same purpose; (3) an acid stantially pure lower boiling anhydride is obchloride and the free acid are reacted; and (4) tained as distillate and thesubstantially pure l0 acetic anhydride and the acid are'reacted; hi h r lin hy ma in h il My roce partakes' of none 0f t outward from which it may be submitted to further rectiindicia of the methods practiced by the industry. iication in order to purify it completely,

I have found that when ketene or a gas mix-. Anoth r m dificatio may be pract d by I ture containing ketene is scrubbed with fatty fluxing the mixed anyhdride until conversion is acids higher than acetic acid, such as pro'pionic, mp and hen separating individual isobutyric, n-butyric, isovalerianic and the like, hydride's by selec ive ab o ion: -'the mixed anyhdride' of acetic acid or of. a homo- Where the ketene contains the same number logous acid and the higher fatty acid is formed. 1 r on atom to the m l cule as the acid In- 'The mixed anhydride'on heating rearranges and dergo ng treatment, it i5 to be ppr cia d at 20 r the separate anhydrides of both acids form. B 110 mixed anhydiide is formed which rearranges distillation these can be separated. its lf by heating. h p rmi ing the recovery The ketene can be employed either in the gase'-' o two c c acid y io i y ous .or liquid. phase, preferably in the former. Such feature s not em by the p t case When so utilized, it may exist in the substantially which is concerned with the intermediate forma 25 1 pure state or be admixed with inert diluents such $1011. f mixed anhydlidee 0f the 10111111181 asmethane andv itshomologues, ethylene and its homologues, CO, $302, N2, 02, airand the like. m-o

The ketene may exist admixed with methane as a result of its formationfrom a ketone 'or with r nr c'o/ Gem and 00 as ,a result of the partial decomposition of. th'e ketene during its manufacture. in which R1 and R: represent diflerent'organic- By k e e is m t a o ound of theme radicals, 101- example, alkyl, aryl, unsaturated 'R=CO, whereR represenfsan organicdivalent alky], mlkyl or unsaturated u l grouping ca as CH2, ,CHsCH and like as Well as containing one or more carbon atoms. 35 their 5 Stitution m'qducts' Substantially equimolecular proportions of the The e introduced into substantial reagents may lie/employed altho an excess of keanhydrous acid since any waterwhich may be me wdum insure the com e plete utilization of the present combines with ketene to form the fatty acid. On the other hand an excess of acid 40 smndmg acid this is waste of may be used without detrimental eflect.

ketene. The .method of contacting the ketene By way of illustration only reference will be with the acid depends on the phase in which, the iv ketene exists, but "is of no great significance. had to preparation higher fatty acid an a hydrides although it is to be understood that such 5: 2 2; :22:22 :13;: 2:23 igzgz i zgg examples are not to be construed in the limitative found it advantageous to scrub the same with sense but rather in the ii theacid undergoing treatment. The reaction is I substantially instantaneous at ordinary condi- 5o tions of temperature and pressure and results Ketene, or gases containin ke te eiscontacted m in the formationof the mixed anhydride. The with a substantially qu m eclfla wei ht of mixed anhydride is heated substantially to its butyric acid, either by passing the gas through a boiling point'in a' still fitted with a fractionating distributor into the acid until the correct amount column and reflux condenser. During this heat- (1. e., equimolecularmmounti s' r i I ing the mixed anhydride rearrangesto a mixture countercurrent-absorption in a tower down which results according to the reaction:

CHaC CHzCO-i-CHaCHzCHzCOOH O cnlcmonzoo By maintaining the temperature at about 140% 150 C. substantially all of the was distilled ofi from the CzH CO b Subtantially none of the mixed anhydride or butyric anhydride distilled over as their boiling points were respectively 155 to 175 C. and 198 199 C. The exact boiling point of the mixed anhydride is uncertain due to the fact that it decomposes quite readily. II

The process was conducted inv an equivalent manner with ketene and propionic acid, resulting in' the formation of propionic anhydride in the still.

My method is'oapable of being carried out with unsaturated acids as acrylic, propiolic, isocrotonic and the like as well as with aromatic alkyl carboxylic acids of the type of cinnamic and phenyl propiolic. Aralkyl carboxylic acids as benzylmalonic, phenylacetic, and aromatic carboxylic acids asbenzoic, toluic and naphthoic acids are also suitable.

While. I have in the foregoing described in some detail the preferred embodiment of my invention'and some variants thereof, it will be understood that this is only for the purpose of making the invention more clear and that the invention is not to be regarded as limited to the details of operation described, nor is it dependent upon the soundness of accuracy of the theories which I have advanced as to the results attained. On the other hand, the invention is to, be regarded as limited only by the terms of the claims, in which it is my intention to claim all novelty inherent therein as broadly as is possible in view of the prior art.

I claim as my invention:

1. A processor preparing acid anhydrides which comprises reacting a ketene with a carboxylic acid containing at least two carbon atoms and con} taining a different number of carbon atoms than the ketene, in a quantity suflicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride oi said 'carboxylic acid.

. 2. A process of preparing acid anhydrides which comprises reacting a ketene with analiphatic carboxylic acid containing more than'two carbon atoms in a quantity suflicient to react with mixture so as to obtain an anhydride Of said carboxylic acid.

2,007,042 acid is: flowing. In either case mixed anhydride 3. A process of preparing acid anhydrides which comprises reacting a ketene with an arcmatic carboxylic acid containing a difierent number of carbon atoms than the ketene in, a quantity suiiicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid.

4. A process of preparing acid anhydrides which comprises reacting a ketene withan aliphatic carboxylic acid containing at least two carbon atoms and containing a difierent number 7 as to obtain an anhydride of said carboxylic acid. I

- 6. A process of preparing acid anhydrides which comprises reacting CH2=C=O with a saturated aliphatic carboxylic acid containing more than two carbon atoms in a quantity sufiicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid.

7. A process of preparing acid anhydrides which comprises reacting CH2=C=O with a carboxylic acid containing more than two carbon atoms in a quantity sufficient to react with any free acid radical and any reactive substituent which'may-be present, heating the reaction mixture under reflux and distilling off acetic anhydride.

8. A process of preparing acid anhydrides which comprises reacting a ketene diluted with an inert gas with a carboxylic acid containing at least two carbon atoms and containing a different number of carbon atoms than the ketene in a quantity suificient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said. carboxylic acid.

9. A process of preparing acid anhydrides which comprises reacting CH2=C=O diluted with an inert gas with a carboxylic acid containing more than two carbon atoms in a quantity suflicient to react with any free acid radical and any reactive substituent which may be present, heating the reaction mixture under reflux and distilling oil acetic anhydride.

10.- A process of preparing acid anhydride which comprises reacting a ketene in the gaseous state with a substantially anhydrous carboxylic acid containing at least two carbon atoms and containing a different number of carbon atoms than the ketene in a quantity suflicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid.

.11. A process of preparing acid anhydrides which comprises reacting CH2=C=O in the gas- .eous state with a substantially anhydrous carboxylic acid containing more than two carbon atoms in a quantity sufiicient to react with any substituted'hydrocarbon carboxylicacid containfree acid and reactive substituent ing more than two carbon atoms in a quantity dride.

12. A process oi preparing acid anhydrides which comprises reacting a ketene with an \msubstituted-hydrocarbon carboxyiic acid containing at least two carbon atoms and containing a different number of carbon atoms than the ketene.

in a quantitysuflicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid.

13. A process of preparing acid anhydrides which comprises reacting a ketene with an uncarboxylic acid.

-suiiicient to react with any free acid radical and any reactive substituent which may be present.

and heating the reaction mixture so as to obtain 7 containing at least two carbon atoms and'containing a diiierent number of carbon atoms than the ketene ina quantity suiiicient to react with any tree acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to-obtain an anhydride of said DI SIMO- v DISGLAIMER 2,007,642.'-M art in de Simo, Berkeley ,'Calif; Pnocns s 'roa rim Manor-Across or CannoxYuo Acrn ANnYnRrnEs. Patent dated July 9, 1935. Disclaimer filed October 25, 1937, by the assignee, Shell Development Company. Hereby disclaims and enters this disclaimer to of claim-6 ct .saidLetters Patent; also disclaims and enters this disclaimer to: r

as much of claim 1 of said Letters Patent as is in excess of the following: A process of preparing acid anhydrides which comprises reacting a ke ne containing at least three carbon atoms with a carboxylicacid containing at least wo carbon atoms and containing a different number of carbon atoms than the ketene, in

aquantity sufficient to react with any free acid radical and any reactive substituent j which may be resent, and heating the reaction mixture so astoobtainan anhydrrde .of said carboxy ic acid;

as much of claim 2 of said Letters Patent asis in excess of the following: I

A 'process of preparing acid anhydrides which comprises reacting a ketene containing at'least three carbon atoms with analiphatic carboxylic acid containing more than two carbon atoms in a quantity sufiicient to react. withany free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid; a v

as much of clai m 3 of said Letters Patent as is in excess of the following; a

A process of preparing acid anhydrides which comprises reacting 'a ketene contraining at least three carbon atoms with an aromatic carb'oxylic'acid" containing a.

difierent number of carbon atoms than the ketene, in a quantity'sufiicient-toreact with any free acid radical and any reactive substituent which may be present, and

' heatingthe reaction mixture so as toobtain an anhydrideof said carboxylic acid as much of claim 4 of said LettersPatent as is in excess of the following:

A process of preparing acid anhydrides which comprises reacting aiketene contwining at least three carbon atoms withan aliphatic carboxylicacid containing at least two carbon atoms and containing a different number of carbon atom's'thanthe ketene, in a quantit sufiicie'nt .to react withany free acid radical and. any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anhydride ofsaidcarboxylic acid-;- s v as much of claim 5 ofsaid Letters Patent as is in excess of the following:

A process of preparing acid anhydrides which comprises, reacting a ketene containing at least three carbon atoms with a saturated aliphatic carboxylic acid con-- taining at least "two carbon atoms and containing'a differentnumbe of vcarbon-atoms than the ketene, in a quantity sufficient to react with any free aci radical and any reactive substituent-which may be present, and heating the reaction mixture soas to obtain an anhydride of said carboxylic acid as much of laim 10 of said Letters Patent as is in excess of the following:

' A process of preparing'acid anhydrides which comprises reacting a ket'enecon-' taining at least three'carbon atoms in the gaseous state with a substantially anhydrous carboxylic acid containing at least two carbon atoms and containing a different number of carbon atoms than the ketene, in a quantity sufficient to react with any free. acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtainan anhydride of said carboxylic acid;

- as much fclaim 12 of said LettersPatent as is in excess of the followingz 1 A process of preparing acid anhydrides which comprises'reacting a ketene'con-. taintng at least three carbon atoms with an unsubstituted hydrocarbon carboxylic acid containing at least two carbon atoms and 'containinga different number of carbon atoms than the ketene, in a. quantity sufficient to react with any free acid radical and any reactive jsubstituent which may be present, and heating the reaction mixture so as to obtain an anhydride of said carboxylic acid;

asmuch of claim 13 of said Letters-Patent as is in excess of thef ouowing: r

:A process of preparing acid anhydrides which comprises reacting a ketene contatntng at leastthre'e carbon atoms with an unsubstituted hydrocarbon carboxyhc .acid containing more than two carbon atoms. in a quantity sufficient to react with any free acid radical and anyreactive substituent which may be'present, and heating the reaction mixture so as to obtain an anhydride of said carbox lic acid;

and as much of claim 14 of said Letters Patent as is in excess 0 the following:

. A process of-preparing acid anhydrides which comprises reacting a ketene con;- taining at least three carbon atoms with an unsubstituted hydrocarbon monocarbox 11c acid containing at least two carbon atomsand containing a differentnumber of car on atoms'than the ketene, in a-quantity sufiicient to react with any free acid radical and any reactive substituent which may be present, and heating the reaction mixture so as to obtain an anh dride'of said carboxyhcacid.

.-[Oflicta Gazette, November '30, 1.987.] 

